BAKERSFIELD — The FBI launched an investigation Tuesday into the death of a man who was beaten by authorities amid questions over whether officials tampered with cellphone videos confiscated from witnesses.

Kern County Sheriff Donny Youngblood said he asked the FBI to get involved after learning that one of two phones seized from witnesses had no footage on it.

Two witnesses told The Times that they watched the videos on each of the phones last week in the wake of David Silva’s death. The case is generating widespread attention because several witnesses have come forward to say deputies ruthlessly beat Silva with batons on the head, even after he was motionless on the ground.

“Our credibility is at stake here,” Youngblood said in an interview. He did not dispute the witnesses’ accounts about the videos but said he would not draw any conclusions until the investigations were complete.

The phones were flown to the FBI’s Sacramento office Tuesday for analysis.

Youngblood said he asked the federal agency to conduct a parallel investigation into Silva’s death, a move he described as unprecedented for his department. The FBI said it had agreed to launch an inquiry and emphasized that it would be independent of the sheriff’s own work.

It appears several videos captured parts of the incident. Last week, KERO-TV broadcast grainy footage from a security camera. The Times on Tuesday reviewed a security video provided by a source, which showed blurry images of figures swinging batons or sticks at a man on the ground.

Youngblood said the Bakersfield Police Department found a video on one of the phones; he asked the department to do the analysis to avoid a conflict of interest. He declined to elaborate on the length or condition of the video, but confirmed that it shows baton blows.

“I have seen the video,” said Youngblood at a news conference Tuesday afternoon. “I cannot speculate whether they acted appropriately or not just by looking at the video.”

“Baton strikes were used but what I don’t know is how many and where they were on the body and if they caused significant injury that caused death,” he added.

Youngblood said the sergeant and six deputies at the scene of the beating had been placed on paid administrative leave, in part because they had received emailed threats.

In interviews Tuesday, the two witnesses insisted that the videos on both phones — each several minutes long — clearly captured deputies repeatedly striking Silva with batons.

“They must have gotten rid of one of the videos,” said Melissa Quair, 31, who told of seeing deputies pummel and kick Silva after confronting him across the street from Kern Medical Center in East Bakersfield. Quair and several relatives and friends were at the hospital because a family member had been in a car crash.

Quair said a phone video shot by her mother showed a deputy trying to block her view of the beating. “She went around him and told him, ‘I’m still recording,’ ” Quair said.

Laura Vasquez, 26, a friend of the Quair family, said she also watched both videos — the other shot by a friend of Melissa Quair — and they vividly depicted the violence she witnessed.

Echoing the account of two other people interviewed, Vasquez said the first two deputies at the scene woke Silva, who was sleeping in front of a house, and ordered him not to move. When Silva sat up, looking confused or scared, a deputy hit him in the head, Vasquez said.

“He fell back and then the other officer got out and swung toward his head,” she said. “Mr. Silva was reaching for his head and the officers said ‘stop moving’ and ‘stop resisting.’ He wasn’t resisting. … He rolled on his back and they kept hitting.”

More deputies and two California Highway Patrol officers arrived at the location. Vasquez said the deputies hogtied Silva, lifted him off the ground and dropped him twice, and delivered more baton blows and kicks to his head and body until he went limp.

“He was screaming for help. He was laying on his chest. The cops were still on top of him, still hitting him. My family and I screamed at them to stop hitting him.… The blood was all over Mr. Silva’s face. We couldn’t even tell if he had eyes or a mouth.”

Vasquez said her girlfriend yelled, ” ‘Somebody call the cops,’ and everybody looked at her and said, ‘They ARE the cops.’ “”

Douglas McNabb and other members of the U.S. law firm practice and write and/or report extensively on matters involving Federal Criminal Defense, INTERPOL Red Notice Removal, International Extradition Defense, OFAC SDN Sanctions Removal, International Criminal Court Defense, and US Seizure of Non-Resident, Foreign-Owned Assets. Because we have experience dealing with INTERPOL, our firm understands the inter-relationship that INTERPOL’s “Red Notice” brings to this equation.

The author of this blog is Douglas C. McNabb. Please feel free to contact him directly at mcnabb@mcnabbassociates.com or at one of the offices listed above.